Earth retaining walls are elongated structures installed along embankments of earth to provide a barrier to slippage or movement of the embankment. Retaining walls are often installed on embankments formed while constructing recessed roadways, parking lots, buildings on terrace-type slopes, and the like. Retaining walls vary in height from a few feet to many tens of feet. The design of the earth retaining walls must account for lateral earth and water pressures, the weight of the wall, temperature and shrinkage effects, and other factors. In addition, the retaining walls typically have an attractive ornamental appearance on an exterior facade. For example, the ornamental design of some facades approximates the look of natural quarried stone. However, a variety of geometric patterns can also be created while forming precast blocks for use in assembling the retaining wall.
Retaining walls have found particular use in terraced construction. Terraced construction involves leveling areas of land and providing a sloping surface of earth between adjacent terraces. Often these terraces are used for constructing buildings, such as apartments or office buildings, and the adjacent terrace provides an area for parking, driveways and the like. The sloping surface between adjacent terraces typically is reinforced in order to prevent slippage of the sloping surface onto the lower terrace and thereby potentially damaging the foundation of the buildings on the upper terrace. Retaining walls are a typical type of reinforcement used on sloping surfaces. The retaining wall used to reinforce the sloping surface varies, including walls constructed of timbers, stones, blocks, and combinations. One type of timber reinforcing wall uses large timbers which are stacked one on top of another against the sloping surface. The stacks of timbers are thereafter secured together, such as with elongated bolts, screws, or pins.
Other retaining walls are assembled from stacks of interconnected cast blocks. Polymeric reinforcement sheets which define elongated lattice-like structures or grids extend laterally from the retaining wall. The grids interlock with the blocks using pins or connectors. The grid is covered with the earth and back fill placed between an interior face of the retaining wall and the earth. The grid thereby secures the wall to the earth and the back fill. However, construction of this type of retaining wall is typically done only for new construction, due to the difficulty and expense of inserting the grids into earth having existing foundations for buildings.
Yet another retaining wall anchors pairs of threaded rods in bedrock of the slope to be covered by the retaining wall. A tubular pipe is connected to the distal ends of the pairs of the rods. Cast blocks are stacked together to form a wall. During construction, a grid is attached to the wall between a first pair of tiers. The grid loops over the pipe between the pairs of rods and is then connected to the wall between two other tiers in an upper portion of the wall. The grid is then placed in tension by moving the pipe along the threaded rods laterally away from the wall. This is accomplished by threading nuts on the rods to push the pipe laterally from the wall. The space between the retaining wall and the slope is filled with earth backfill to lock the wall to the earth. However, this wall is not entirely satisfactory in that the grids significantly increase the cost of the retaining wall. Also, this type of wall requires sufficient space between the interior face of the retaining wall and the slope to be covered by the retaining wall in order for the grids to be stretched tightly to secure the wall to the earth. Further, insufficient space between the retaining wall and the surface to be covered prevents placing enough backfill over grids to lock the wall in place.
Still another type of retaining wall uses a combination of steel I-beams and interlocking wood planks. The I-beams are driven deeply into the earth by pile drivers. The I-beams are disposed with the U-shaped web on the sides of the beam facing laterally along the embankment to be secured by the retaining wall. A plurality of these I-beams are spaced-apart along the embankment. A plurality of wood beams are slidingly received in the webs of a pair of adjacent I-beams.
While these types of retaining walls have functioned over many years for securing earth slopes from slippage and movement, such walls age and decay, and thereby become weakened and have reduced capability for functioning as a retaining wall. Such retaining walls accordingly must be repaired or replaced periodically. In areas having terraced construction however this is a difficult problem. It may be extremely difficult to move the heavy equipment needed for constructing retaining walls into the driveways and parking lots of terraced construction. The foundations of buildings on upper terraces also may interfere with the ability to remove and install the grid-like reinforcing sheets. Removal of a wall for replacement with a new wall risks slope slippage and foundation damage to buildings during construction of the new retaining wall.
Accordingly, there remains a need in the art for an improved retaining wall and method of construction particularly for use in areas having existing buildings. It is to the provision of such that the present invention is directed.